Optical devices, such as illuminating devices and display devices, using LEDs as light sources are used in broad areas. These are usually provided with an LED device in which an LED element is mounted on a circuit pattern on a substrate by an electroconductive adhesive, a solder or the like and necessary interconnection is made through wire bonding. The LED device is provided in the circumference of the LED element with a reflector (reflecting plate) to raise light utility of the LED, and the LED element located in the reflector is encapsulated with a transparent resin.
As white LEDs, there are generally known ones fabricated so as to provide a white color by combining a plurality of LEDs including a green (G: 525 nm), a blue (B: 470 nm) and a red (R: 630 nm), and ones utilizing the action of the wavelength conversion by blending fluorescent substances in an encapsulating resin. In the case of the latter, an ultraviolet light emitting LED is used as a light source in some cases. As reflectors of these white LEDs, a molded object of a resin composition in which a white pigment particle such as a metal oxide is blended is used in some cases. In the case of a resin-made LED reflector, the reflector is demanded to have a sufficient heat resistance to a heating step of heating a solder or the like when an LED element is mounted on a substrate, the heat generation at thermal curing of an encapsulating resin, the heating when an LED device is connected to another member, the heating in an environment using an LED device, and the like.
In consideration of the above-mentioned situation, as materials to form LED reflectors, resin compositions are proposed which contain a liquid-crystal polyester having an excellent heat resistance, and a white pigment (for example, see Patent Literatures 1 to 4).